AMBER Archive (2005)

Subject: Re: AMBER: Error: vlimit exceeded for step

From: Thomas E. Cheatham, III (cheatham_at_chpc.utah.edu)
Date: Tue May 24 2005 - 13:12:58 CDT

> I put wrong info about 20ps point. here, I attach 20ps energies again.
> I really apologize for my mistake.
> In 20ps, it has 299.88, which looks like reasonable temp.
> could you look at this one more time?
> -------------------------------
> check COM velocity, temp: 0.002858 0.01(Removed)
>
> NSTEP = 10000 TIME(PS) = 20.000 TEMP(K) = 299.88 PRESS =
> 0.0
> Etot = -201648.0152 EKtot = 50211.0109 EPtot =
> -251859.0262
> BOND = 898.2060 ANGLE = 2473.6478 DIHED =
> 1351.3450
> 1-4 NB = 826.9863 1-4 EEL = -10156.4761 VDWAALS =
> 32172.4335
> EELEC = -280549.9268 EHBOND = 0.0000 RESTRAINT =
> 1124.7582

If this is correct, and you are indeed running with restraints (as pointed
out on this reflector many times if you search the archive), likely you
have a force constant that is too large leading to SHAKE failure. Try
using a force constant for the restraints of less than 5 kcal/mol. Note
that 1000 kcal/mol of restraint energy is a lot so make sure that you are
restraining to what you want to be restraining too...

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